For the past ten years our research program centered on the exploration of psychoactive characteristics of new drugs through clinical and behavioral methods and on the determination of therapeutic efficacy of new psychopharmacological compounds in psychiatric conditions representing various diagnostic categories. Although the nature of the research program and the general areas of interest are quite similar to those of the original period of support, the specific aims outlined in this renewal application include the testing of hypotheses based on findings during the previous years, the following up of promising leads from research carried out by our own and other groups and the extension of our activities into some of the more neglected areas of clinical investigations with psychotropic drugs. Accordingly, the proposed research aims for a consolidation of therapeutic practices in the field of psychopharmacology, based on systematic studies of optimal indications for known psychoactive drugs; optimal dosages for such agents; interaction and potentiation effects of different drugs; more sensitive, reliable and objective means of establishing the effects of psychoactive drugs on behavior and psychopathology; and systematic studies in such unspectacular but important clinical areas as maintenance therapy and psychogeriatrics.